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[media] em28xx: simplify ID-reading from Micron sensors 

Use i2c_smbus_read_word_data() instead of i2c_master_send() and
i2c_master_recv() for reading the ID of Micorn sensors.

i2c_smbus_read_word_data() assumes that byes are in little-endian,
so, it uses:
	data->word = msgbuf1[0] | (msgbuf1[1] << 8);

However, Micron datasheet describes the ID as if they were read
in big-endian. So, we need to change the byte order in order to
match the ID number as described on their datasheets.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Frank Schaefer 2017-04-16 14:41:52 -03:00 committed by Mauro Carvalho Chehab
parent e7080d4471
commit 4d58443696
1 changed files with 4 additions and 24 deletions
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28
drivers/media/usb/em28xx/em28xx-camera.c
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@ -98,8 +98,6 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
{
int ret, i;
char *name;
u8 reg;
__be16 id_be;
u16 id;
struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
@ -107,10 +105,8 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
dev->em28xx_sensor = EM28XX_NOSENSOR;
for (i = 0; micron_sensor_addrs[i] != I2C_CLIENT_END; i++) {
client->addr = micron_sensor_addrs[i];
/* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */
/* Read chip ID from register 0x00 */
reg = 0x00;
ret = i2c_master_send(client, &reg, 1);
ret = i2c_smbus_read_word_data(client, 0x00); /* assumes LE */
if (ret < 0) {
if (ret != -ENXIO)
dev_err(&dev->intf->dev,
@ -118,24 +114,9 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
client->addr << 1, ret);
continue;
}
ret = i2c_master_recv(client, (u8 *)&id_be, 2);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
client->addr << 1, ret);
continue;
}
id = be16_to_cpu(id_be);
id = swab16(ret); /* LE -> BE */
/* Read chip ID from register 0xff */
reg = 0xff;
ret = i2c_master_send(client, &reg, 1);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
client->addr << 1, ret);
continue;
}
ret = i2c_master_recv(client, (u8 *)&id_be, 2);
ret = i2c_smbus_read_word_data(client, 0xff);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
@ -143,10 +124,9 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
continue;
}
/* Validate chip ID to be sure we have a Micron device */
if (id != be16_to_cpu(id_be))
if (id != swab16(ret))
continue;
/* Check chip ID */
id = be16_to_cpu(id_be);
switch (id) {
case 0x1222:
name = "MT9V012"; /* MI370 */ /* 640x480 */